【摘要】：聚羧酸系減水劑是近三十年發(fā)展起來的新型高性能減水劑,具有摻量低、減水率高、保坍性好、收縮率低、增強效果好及不污染環(huán)境等優(yōu)良性能,被認為是未來混凝土外加劑發(fā)展的方向。本文采用活性單體共聚法合成聚羧酸系減水劑,首先制備具有聚合活性的聚乙二醇單甲醚甲基丙烯酸酯大分子單體,再在過硫酸銨的引發(fā)作用下將其與甲基丙烯酸和甲基丙烯磺酸鈉共聚,得到目標產物。通過正交試驗和單因素試驗,采用較為準確的酯化率計算方法,得到大單體的最佳酯化工藝參數(shù)：甲基丙烯酸和聚乙二醇單甲醚(分子量1000)的摩爾比為2.5：1,催化劑對甲苯磺酸的用量為甲基丙烯酸和聚乙二醇單甲醚總質量的3%,阻聚劑吩噻嗪用量為甲基丙烯酸質量的2%,酯化溫度120℃,酯化時間6h,酯化率達95.37%。表征了大單體的分子結構,討論了大單體的儲存條件。 聚羧酸系減水劑的合成工藝為：甲基丙烯酸和酯化大單體的摩爾比為3：1,甲基丙烯磺酸鈉用量為單體總質量的12%,引發(fā)劑用量為單體總質量的5%,聚合溫度85℃,單體混合溶液和引發(fā)劑水溶液分別均勻滴加,滴加時間1-2h,保溫時間3h。聚羧酸系減水劑的勻質性和混凝土應用性能測試結果表明：摻量為0.5%,水灰比為0.29時,聚羧酸系減水劑表現(xiàn)出良好的分散性和分散保持性,混凝土和易性較好,后期增強效果顯著。 相比于天然骨料,再生骨料具有表觀密度低、吸水率高、壓碎指標高等特點。采用再生骨料配制的再生混凝土用水量大,硬化后強度低、彈性模量低,只能應用于一些非承重構件和普通承重構件。為擴大再生混凝土的應用范圍,須對再生骨料進行強化改性。 本文采用純水泥漿、水泥外摻硅粉漿液、水泥外摻Ⅰ級粉煤灰漿液、水泥外摻聚羧酸系減水劑漿液四種礦物漿液對再生粗骨料進行強化試驗,結果表明：經(jīng)過強化后的再生粗骨料的表觀密度較強化前有所提高,壓縮指標降低,相比于其他三種化學漿液,水泥外摻聚羧酸系減水劑漿液的強化效果更好。聚羧酸系減水劑強化改性后的再生粗骨料配制的再生混凝土較原生再生粗骨料配制的同強度等級、同取代率的再生混凝土,具有坍落度控制更好,抗壓強度和彈性模量更高的特點,滿足再生混凝土的施工和應用要求。這表明將聚羧酸系減水劑運用在再生混凝土中,對于拓寬再生混凝土的應用范圍,緩解資源環(huán)境難題,實現(xiàn)混凝土行業(yè)的可持續(xù)發(fā)展具有積極意義。
[Abstract]:Polycarboxylic acid superplasticizer is a new type of high performance water reducing agent developed in recent 30 years. It has good properties such as low dosage, high water reducing rate, good collapse retention, low shrinkage, good enhancement effect and no pollution to the environment. It is regarded as the development direction of concrete admixture in the future. In this paper, poly (carboxylic acid) series water reducer was synthesized by copolymerization of active monomer. The macromolecular monomer of poly (ethylene glycol monomethyl ether) methacrylate with polymerization activity was first prepared. The target product was obtained by copolymerization of ammonium persulfate with methacrylic acid and sodium methacrylate sulfonate. By orthogonal test and single factor test, the optimum esterification parameters of macromonomer were obtained by using more accurate method of esterification. The molar ratio of methacrylic acid and polyethylene glycol monomethyl ether (molecular weight 1000) was 2.5: 1. The amount of catalyst p-toluenesulfonic acid is 3% of the total mass of methacrylic acid and polyethylene glycol monomethyl ether, the amount of the inhibitor phenothiazine is 2% of the mass of methacrylic acid, the esterification temperature is 120 鈩，

本文編號：2316788